One major challenge when working with immobilized biomolecules as for example proteins like antibodies in diagnostic and therapeutic applications is to maintain the activity of the biomolecules. However, since the chemical, physical or physiological properties of bio-functional molecules are often significantly altered by variations in the compounds' surrounding environment, this is a difficult task. For example, changes in pH, ionic strength, temperature or storage can result in reversible or irreversible changes in the character of compounds. Especially biomolecules which are subjected to stress like e.g. long-term storage, transport or sterilization procedures have to be stabilized in order to prevent a loss of activity.
For clinical immunodiagnostics, a sufficient stabilization of immobilized biomolecules that are used in diagnostic assays is required for the market entry of products according to the ‘EU In Vitro Diagnostics Guideline’ (IVDD 98/79/EC).
Implantable medical devices containing immobilized biomolecules, for example, are exposed to a wide variety of biological agents present in the tissues of the body, e.g. acids, bases, ions and the like, depending on the location of the implant in the body. Some of these agents can degrade the bio-molecules of the device leading to damage or even device failure.
Commercially available carriers or devices containing immobilized biomolecule preparations therefore contain stabilizers like sugars (e.g. trehalose) and/or serum-derived proteins (e.g. albumin) in order to protect bio-molecules from degradation (Polifke T. & Rauch P, Laborwelt (2007) Vol. 6, pp 1-4).
Stabilizers that contain serum-derived proteins have the advantage that, in addition to their stabilizing effect, they also function as blocking agents to prevent unspecific binding. However, as albumins and the like are of human or animal origin, they may contain pathogens like for example viruses or prions. Therefore, complex cost and time intensive purification methods have to be applied in order to remove these pathogens.
Another disadvantage of conventional methods for preventing damage to immobilized biomolecules during stress like sterilization or long-term storage is that these methods require that said biomolecules be frozen (U.S. Pat. No. 5,730,933; Cleland J. L. et al., Journal of Pharmaceutical Sciences (2001) Vol. 90, No. 3, pp. 310-321). For example, U.S. Pat. No. 5,730,933 discloses a method for sterilizing antibodies, by which the activity of these antibodies can be retained by freezing them during sterilization. However, freezing can lead to conformational changes of the biomolecules that can affect their biofunctionality and constitutes a further step in the preparation of immobilized biomolecules causing additional costs. Furthermore, the stabilizing composition contains serum proteins like albumin which are of animal origin and therefore bear the risk of contaminating the biomolecules which are incubated therein.
Therefore, a need exists for improved methods and means for stabilizing and protecting immobilized biomolecules that are used in therapy and diagnosis. Thus, the object of the invention is the provision of methods and means for the stabilization of biomolecules that avoid the disadvantages of the state of the art.